Mr Abbott has called on Labor to "repent" its commitment to an ETS and respect what he believes is the mandate the Coalition earned at the September 7 election.

But Mr Shorten told reporters in Canberra: "Labor will never be a rubber stamp for Tony Abbott. We accept the science of climate change. Tony Abbott doesn't.

"We decide our policies based on a long-held principle that climate change is real. We also want to build a modern economy for the future and not put off to future generations the challenges we should be dealing with now."

However, Mr Shorten is expected to lose the legislative battle when a new Senate is introduced in July and Labor and Greens lose the numbers needed to block government bills.

The Government wants to scrap the entire carbon pricing system, which it calls the carbon tax, by next July and introduce Direct Action which would use payments to companies to cut pollution.

Labor wants to dump its fixed carbon price - which is what it refers to as the carbon tax - and move to an ETS with a floating price set by the market.

Mr Shorten said no credible expert believes Direct Action would succeed in reaching the bipartisan target of a 5 per cent reduction of carbon emissions on year 2000 levels by 2020.

Shadow environment minister Mark Butler said there had been a strong message from big business that it wanted a mechanism such as the ETS which it could trade overseas. He said this would be the most effective way for them to work.